Eisai's files for approval of potential insomnia disorder treatment in Japan

Japanese drugmaker Eisai (TYO: 4523) says it has submitted marketing authorization application in Japan for lemborexant, an investigational agent for sleep-wake regulation, seeking approval for use in the treatment of insomnia disorder.

This application was based on the results of two pivotal Phase III clinical studies in patients with insomnia, SUNRISE 1 (Study 304) and SUNRISE 2 (Study 303), enrolling around 2,000 patients combined, as well as important safety studies, including assessment of postural stability after middle-of-the-night awakening, and a next-morning driving study (Study 106, Study 108).

Eisai and its USA-based co-developer Purdue Pharma filed for US approval of the lemborexant in January of this year.

SUNRISE 1 was a placebo-controlled 1-month Phase III clinical study evaluating the efficacy and safety of lemborexant versus zolpidem tartrate extended release (zolpidem ER) in 1,006 male or female adult patients 55 years and older (45% of patients were 65 years and older) with insomnia disorder, which was characterized by difficulty staying asleep.

The study objectively assessed sleep latency (time taken between going to bed and falling asleep, primary objective), sleep efficiency and wake after sleep onset (effect on maintaining sleep, secondary objectives) using polysomnography. The results of the study showed that lemborexant 5mg and 10mg had statistically significant improvement compared to zolpidem ER 6.25mg and placebo in sleep parameters evaluated in primary and key secondary objectives. In this study, lemborexant had rates of discontinuation due to adverse events (AEs) comparable to placebo, with the most common AEs in the lemborexant arms being headache and somnolence.

It is estimated that approximately 1 in every 5 people (over 20 million people) in Japan suffers from a sleep disorder, and the number of patients being examined at medical institutions continues to increase.